The present invention relates to power switches, and in particular to semiconductor power switches, particularly power MOSFET switches. The present invention has particular application to intelligent power switches which are power switching devices that include intelligent protective circuits to prevent damage in the event of overtemperature and overcurrent conditions.
Intelligent power switches employ charge pumps which are well known circuits to charge current into the gate of the power switching device in order to maintain the power switch on continuously. In particular, charge pumps are necessary for high side NMOS switches when a voltage above the supply voltage needs to be generated. Further, in a pulsed mode of operation, the maximum frequency of operation of intelligent power switches has been limited to about 1 khz for silicon integrated charge pumps because pump capacitor values are small and cannot generate large gate currents even when operating in the MHz range.
It would be desirable to provide a power switching device, for example, an intelligent power switching device, which is capable of continuous on operation, when desired, and which can also be switched at frequencies much higher than heretofore possible, for example, in the range up to 20 kHz to 50 kHz.
It is furthermore desirable to provide such a power switching device that is suitable for use in an automotive environment.